The field of the invention is that of RF communication between a controller and a set of autonomous automated vehicles transporting materials within a building or other location; in particular transporting a load along a track in a remotely controlled vehicle.
In the field of material transport through automated vehicles, it is necessary for a controller to communicate with individual ones of the vehicles to tell it to start, follow a certain path to a destination and to unload.
Communication between the controller and the individual vehicles is plagued by noise and other interference.
In the past, the RF link was completed with low frequency wireless communication, typically not in compliance with an FCC standard.
Various suppliers use infra-red optical links, ethernet or other relatively low RF frequency communications.
These systems suffer from cross talk between different vehicles, loss of signal, short range (line of sight) or a requirement of physical contact between the vehicle and an antenna or other means of carrying the control signals.
In one example, cross talk between individual vehicles results in vehicle A obeying a command to stop that was intended for vehicle B, with the result that vehicle A is stranded in a place where it does not belong.
In another example, vehicle A could obey a command to start that was received at an inopportune time—e.g. during a loading process.
Similarly, in a common approach to vehicle control, the vehicle is not left alone to proceed to a destination, but is periodically told to continue moving, with the fail-safe response to stop (for safety reasons). If contact is lost with the controller, the vehicle will be stranded between a start location and an end location.
Optical systems require that there be a straight line between the controller or relay points for controller signals and the sensor on the vehicle. In a dirty factory environment, the sensor may become coated with dust and unable to sense signals.
Conventional present-day systems use open-loop technology, in which the vehicle is told to start moving and then continues until it reaches its destination or suffers a malfunction.
Control signals are conventionally broadcast throughout a relatively large factory space, with potential for causing interference with other equipment that responds to a signal meant for the material handling system.
Since the controller doesn't know where individual vehicles are, collision avoidance requires a conservative margin of safety such as permitting only one vehicle at a time to operate within a relatively large area.
The art could benefit from a closed-loop system that is resistant to noise and has a high degree of separation for simultaneous operation.